Yellow Vein Mosaic disease in kenaf (Hibiscus cannabinus l.) under different sowing dates in two agroecologies

Determination of appropriate sowing dates is an important approach towards obtaining optimum crop yield as it affects the resistance/susceptibility of crops to insect pests and diseases. The study investigated the effect of three sowing dates (May, June and July) on the occurrence and incidence of yellow vein mosaic disease in kenaf variety (IFEKEN-100) planted in the experimental fields of the Institute of Agricultural Research and Training (IAR&T) located in Ibadan and Ilora. The incidence of yellow vein mosaic disease was high in May at the two locations with means of 25 and 30% for Ibadan and Ilora, respectively. Plant height was not significantly different in the two locations across the three months. The highest stem diameter was obtained in May from Ilora and Ibadan with means of 1.44 and 1.53 cm, respectively. The best bast fiber yield was recorded in June at Ibadan with a mean value of 1.72 tha-1. Nucleic acid spot hybridization (NASH) was used to confirm the disease and the results revealed that Begomovirus was present in kenaf sowm in the two locations during the period of the three months except in kenaf sown in July at Ilora. The results of this study revealed the importance of sowing dates on the occurrence of viral diseases on the field. If the sowing date is optimum, the effect of viruses may not be pronounced in the crop as seen in the month of June having relatively low virus incidence as well as the highest plant height and bast fibre yield.Keywords: Begomovirus, kenaf, nucleic acid hybridization, yiel